THRESHOLD VALUES OF SHEAR STRENGTH PARAMETERS OF SOILS TAKEN FROM SLOPE FAILURES AND STABLE SLOPES IN MALAYSIA

The reduction of shear strength parameters of the soil in the slopes as well as the reduction of suction as the soil become saturated during prolonged rainy seasons are the two main causes of slope failures in Malaysian residual soils. In this study, a total of 227 shear strength parameters were obtained from 29 slope failures in Penang Island and Baling. Both locations are located in Northern Malaysia. In addition, 35 shear strength parameters were also obtained from 10 stable slopes, also at the same locations. Disturbed soil samples were taken at a depth of 100mm from the existing ground surface. Field bulk density tests were carried out at all the location where soil samples were taken. The field bulk density results were later used to re-compact the soil for the consolidated drained shear box tests to be carried out in laboratory. The objective of the research is to determine the threshold values of the effective shear strength parameters of soil taken from both the slope failures and stable slopes. The threshold values of the effective shear strength parameters of the soil slopes were determined after comparing the effective soil shear strength parameters taken from slope failures and stable slopes. It was found that, the threshold value for the effective cohesion c' was 0.0 kN/m 2 while the threshold value of effective friction angle O' was 23.2 0 .